Researchers from the Research Institute for Chromatography (Kortrijk, Belgium) and AstraZeneca R&D Charnwood (Loughborough, UK) used in-situ derivatization and liquid chromatography–mass spectrometry (LC–MS) to analyze arylamines and aminopyridines, which can be present as potentially genotoxic impurities in pharmaceutical preparations at trace levels. The method included a derivatization procedure using hexylchloroformate followed by reversed-phase LC with single-quadrupole MS in the selected ion monitoring mode. They found that the derivatized compounds exhibited better chromatographic behavior.